extras/volume_id/lib/squashfs.c

   1 /*
   2  * volume_id - reads filesystem label and uuid
   3  *
   4  * Copyright (C) 2006 Kay Sievers <kay.sievers@vrfy.org>
   5  *
   6  * This program is free software: you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation, either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #ifndef _GNU_SOURCE
  21 #define _GNU_SOURCE 1
  22 #endif
  23
  24 #include <stdio.h>
  25 #include <stdlib.h>
  26 #include <unistd.h>
  27 #include <string.h>
  28 #include <errno.h>
  29 #include <ctype.h>
  30
  31 #include "libvolume_id.h"
  32 #include "libvolume_id-private.h"
  33
  34 #define SQUASHFS_MAGIC          0x73717368
  35 #define SQUASHFS_MAGIC_LZMA     0x71736873
  36
  37 struct squashfs_super {
  38         uint32_t        s_magic;
  39         uint32_t        inodes;
  40         uint32_t        bytes_used_2;
  41         uint32_t        uid_start_2;
  42         uint32_t        guid_start_2;
  43         uint32_t        inode_table_start_2;
  44         uint32_t        directory_table_start_2;
  45         uint16_t        s_major;
  46         uint16_t        s_minor;
  47 } PACKED;
  48
  49 int volume_id_probe_squashfs(struct volume_id *id, uint64_t off, uint64_t size)
  50 {
  51         struct squashfs_super *sqs;
  52
  53         info("probing at offset 0x%llx\n", (unsigned long long) off);
  54
  55         sqs = (struct squashfs_super *) volume_id_get_buffer(id, off, 0x200);
  56         if (sqs == NULL)
  57                 return -1;
  58
  59         if (sqs->s_magic == SQUASHFS_MAGIC || sqs->s_magic == SQUASHFS_MAGIC_LZMA) {
  60                 snprintf(id->type_version, sizeof(id->type_version), "%u.%u",
  61                          sqs->s_major, sqs->s_minor);
  62                 goto found;
  63         }
  64         if (sqs->s_magic == bswap_32(SQUASHFS_MAGIC) || sqs->s_magic == bswap_32(SQUASHFS_MAGIC_LZMA)) {
  65                 snprintf(id->type_version, sizeof(id->type_version), "%u.%u",
  66                          bswap_16(sqs->s_major), bswap_16(sqs->s_minor));
  67                 goto found;
  68         }
  69
  70         return -1;
  71
  72 found:
  73         volume_id_set_usage(id, VOLUME_ID_FILESYSTEM);
  74         id->type = "squashfs";
  75         return 0;
  76 }